Pre-Exposure Rabies Booster • After a full primary series (typically 2 doses), a booster is usually given after 1 year. • After that booster, protection generally lasts for up to 3 years, possibly longer. Post-Exposure Prophylaxis (PEP) Boosters • If a person previously had a complete pre-exposure or post-exposure course, and is re-exposed: • Only 2 booster doses (on days 0 and 3) are needed. • These provide immediate and robust protection. • After such boosters, immunity can persist for years, but another booster would be required if exposed again much later.

Well it depends upon Individual immune response and risk of exposure. A titer test can help determine if the person still has adequate immunity.

Each brand has it own valid period it varies from 1 to 3 years and individual immunity is also will be taken in to consideration. So whenever there exposure within valid period we will take titer test to confirm the immunity and take next step